When I install software I am implicitly trusting it, whether that software is trustworthy or not. If it is exploitable that doesn't mean I didn't trust the software. On my personal computer, the expectation is that only the software I have implicitly trusted will be running. If I install something that isn't trustworthy but trust it anyway it's game over. If it's exploited, that's a different issue to trusting it.
Shared VMs are a totally different ball game. All of a sudden I am sharing resources with a potentially bad actor.whethrt or not I trust them is kind of indifferent, I don't get to choose who I colocate with, and ultimately that's the difference.
Being pedantic about this is not helping anyone actually be more secure: the odds are orders of magnitude greater that someone will be compromised by a different security problem than by the diminishing returns trying this attack against a current browser, and that the attacker will directly obtain the data they want without needing a side-channel attack.
What code do you actually trust? (to be incorruptible/unhackable, etc)